Source: BTS for port of entry data. Truck flows simulated by Matisziw, T.C. (2005) Modeling Transnational Surface Freight Flow and Border Crossing Improvement, The Ohio State University.
NAFTA truck flows are quite revealing of the relationships between land gateways and their hinterland, which occurs along corridors (NAFTA corridors). Most of the traffic along the US Mexico border tends to be of short distance, supplying in finished or semi-finished goods Southern California, Arizona, New Mexico and Texas. There is also a long distance corridor reaching the manufacturing belts of the Midwest and the South. Canadian truck flows illustrate a similar pattern in the Northeast while Northwest flows are more commodity related.